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The number of buckets on the periphery of a Pelton wheel is given by
(D/2d) + 5
(D/2d) + 10
(D/2d) + 15
(D/2d) + 20
(D/2d) + 5
(D/2d) + 10
(D/2d) + 15
(D/2d) + 20